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Ch. 10 - Infinite Sequences and Series
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 10, Problema 10.2.64

Which series in Exercises 53–76 converge, and which diverge? Give reasons for your answers. If a series converges, find its sum.
∑ (from n = 1 to ∞) (1 − 1/n)ⁿ

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First, identify the general term of the series: \(a_n = \left(1 - \frac{1}{n}\right)^n\).
Next, analyze the behavior of the term \(a_n\) as \(n\) approaches infinity by finding the limit \(\lim_{n \to \infty} \left(1 - \frac{1}{n}\right)^n\).
Recall the known limit \(\lim_{n \to \infty} \left(1 - \frac{1}{n}\right)^n = e^{-1}\), which is a nonzero constant.
Since the terms \(a_n\) do not approach zero, apply the Divergence Test (also called the nth-term test for divergence), which states that if \(\lim_{n \to \infty} a_n \neq 0\), then the series \(\sum a_n\) diverges.
Conclude that the series \(\sum_{n=1}^\infty \left(1 - \frac{1}{n}\right)^n\) diverges because its terms do not tend to zero, so it does not converge and therefore does not have a finite sum.

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